The present invention relates to a biological optical measurement technique for measuring a metabolite concentration of a living organism or its change in the concentration by using light, and particularly relates to a biological optical measurement probe for measuring the metabolite concentration of a head part of a subject, and a biological optical measurement instrument using the same.
The techniques of measuring change in a blood amount in a cerebral cortex accompanying brain activity at a number of points, and displaying the change in the blood amount as a moving image and a static image (biological optical measurement instruments) have been already proposed in “Medical Physics, vol. 22, No. 12, pp 1997-2005 (1995)” and “Proceedings of SPIE, vol. 3597, pp 230-237”. Each of the arts uses a square probe in which incident optical fibers and detection optical fibers are alternately arranged in a tetragonal lattice shape.
Since it is difficult to bring the probe in the tetragonal lattice shape as described above into close contact with a substantially spherical head part, the following proposals have been already made.
(1) JP-A-2001-286449 describes a probe for a biological optical measurement instrument which has branched portions extended into branch shapes from a linking axis, and fits to the shape of a head part.
(2) JP-A-2002-143169 describes probes for a biological optical measurement instrument characterized in that linking parts of probes arranged in a lattice-shape rotate, and a holding part which holds each of the probes has elasticity.
(3) JP-A-2002-11012 describes a probe which covers an entire head part by filling a plurality of regions of the head part with tetragonal lattices, and gaps between them are filled with polygons.
(4) JP-A-2002-502653 describes an instrument for measuring a brain tissue of a subject in a non-invasive manner by arranging probes on a head part of the subject in a geometrical pattern.
(5) JP-A-2004-121702 describes a probe with incident optical fibers and detection optical fibers arranged in rhombic shapes, which covers an entire spherical head part by using four sets of the rhombic shapes, and is capable of displaying a portion corresponding to a brain by one image.
(6) JP-A-2006-158480 describes a probe which allows optical fibers located at the outer periphery of the probe to be placed at substantially the same position on a head part, for example, directly above the ears, even when the size of the head changes, by forming gaps by removing some of the connecting members connecting incident optical fibers and detection optical fibers and some of the optical fibers, and changing the distances between the optical fibers arranged around the gaps.